This invention relates to a method for determining a level of particulate material in a particulate contaminate material collection vessel and a particulate contaminate material collection vessel having a particulate contaminant material level indicator.
In the operation of copier/duplicator machines, it is necessary to provide a system for the recovery of particulate contaminants from inside the copier/duplicator machine. These contaminants may comprise particulate materials as varied as paper dust, toner, developer and the like. These particulate materials can vary substantially in their density and in other properties. Such particulates are typically recovered from copier/duplicator machines by a vacuum system which passes the air streams recovered from the inside of the copier/duplicator machine to a cyclone separator where particulates are separated with the gaseous components of the stream being withdrawn and passed to further filtration and the like. The particulates recovered from the cyclone separator are typically deposited in a collection vessel beneath the cyclone separator, although in some instances it is possible to position a cyclone separator in other than a vertical position. These particulates accumulate in the collection vessel and are periodically dumped from the collection vessel. In the event that the particulates accumulate in the collection vessel to an unacceptably high level, the failure to empty the collection vessel can lead to a toner blow out condition that contaminates the machine and the machine site. Such contamination in the copier/duplicator machine is very undesirable and creates many problems.
Unfortunately, the composition of the particulates collected in the collection vessel can vary widely from paper particulates to toner to developer. There is a wide disparity in the behavior of these various types of solids as well as in their density. Accordingly, attempts to use level control or detection systems such as Piezo electric systems have been relatively unsuccessful because they are relatively fragile and provide very short service lives. Similarly optical systems have been unsuccessful because the paper dust tends to form clouds and create false readings at the selected level for monitoring the particulates level in the collection vessel. Further weight systems are relatively inaccurate and can result in overfilling because the weight may be determined based upon a mixture of particulates which is more dense than those in fact collected. Further weight systems tend to be relatively inaccurate since they involve mechanical mounting and the like.
As a result, a continuing effort has been directed to the development of improved methods and apparatus for determining the level of particulate material in a particulate material collection vessel and for generating a signal to indicate the high level of particulates in the collection vessel.
According to the present invention, the level of particulate material in a particulate material collection vessel is readily determined by a method comprising: positioning a transmitter to transmit an acoustic wave signal through a particulate storage area in the vessel at a selected level to a receiver; providing electrical power to the transmitter; monitoring an acoustic wave signal received at the receiver to detect a change in the acoustic wave signal indicative of particulate material at the selected level in the particulate material storage area; and, generating a signal indicative of the presence of particulate material at the selected level in the particulate material storage area.
The present invention further comprises a particulate collection vessel having a particulate material level indicator and comprising: a vessel having a particulate material inlet, the inlet being configured for connection to a cyclone separator particulate material outlet; a transmitter transducer acoustically coupled to the vessel or positioned inside the vessel at a selected level and adapted to transmit an acoustic wave signal across at least a portion of a particulate material storage area inside the vessel; a receiver acoustically coupled to the vessel or positioned inside the vessel at the selected level and adapted to receive the transmitted acoustic wave signal; and, a comparator connected to the receiver and adapted to generate a signal responsive to a change in the acoustic wave signal indicative of particulate material in the particulate material storage area at the selected level.